To enhance the low-temperature activity and anti-sintering performance of Ni-based catalysts for CO methanation, mesoporous CeO₂ supports with a confined structure were synthesized via a hydrothermal method. The effects of three Ni loading methods—incipient wetness impregnation, co-precipitation, and bis(cyclopentadienyl)nickel sublimation—on catalytic performance were systematically compared. Characterization techniques, including X-ray diffraction (XRD), N₂ adsorption-desorption test, hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), revealed the critical influence of the loading method on Ni species dispersion, particle size, and metal-support interaction. The results indicated that all three mesoporous Ni/CeO₂ catalysts exhibited excellent anti-sintering properties due to the confinement effect of the support. However, their low-temperature activities differed significantly, primarily determined by the specific state of Ni. In the NC-B catalyst prepared by bis(cyclopentadienyl)nickel sublimation, the interaction between Ni species and the support was relatively weak. After reduction, this method yielded highly dispersed metallic Ni nanoparticles, increasing the number of low-temperature active sites. Consequently, the NC-B catalyst achieved 98% CO conversion rate and 100% CH₄ selectivity at 300 ℃, demonstrating the optimal low-temperature methanation performance.